This invention relates to a detector mounting assembly in a spectrometer and more particularly to a three-axis adjustment mounting assembly for precisely aligning a spectrometer detector relative to a radiation beam.
In analytical instruments such as spectrophotometers, it is necessary that the detector be precisely aligned with the radiation exiting from the sample chamber in order to generate an accurate signal. For example, in a typical Fourier transform infrared (FT-IR) spectrophotometer, infrared radiation from an infrared emitting source is collected, passed through an interferometer, passed through the sample to be analyzed, and finally brought to focus on an infrared detector. In systems utilizing adjustable optical elements, the mirrors are adjusted to align the radiation onto the detector. In systems where the optical elements are fixed, the detector must be aligned to the radiation beam. Fixed optical systems offer significant advantages such as economy of manufacture and ease of replacement of optical elements in the field. However, it is necessary that the detector be adjustable both vertically and horizontally for precise positioning in the optical beam and also adjustable along the optical beam for proper focus of the beam thereon.
Accordingly, it is an object of the present invention to provide a new and approved spectrometer detector mounting assembly which affords three-axis adjustment of the detector.
A further object of the invention is to provide such a detector mounting assembly which is highly precise in alignment adjustment.
Another object of the invention is to provide such a detector mounting assembly which affords convenient access for three-axis adjustment.
A further object of the invention is to provide such a detector mounting assembly which is economical to manufacture and which utilizes a minimum of components.
Other objects will be in part obvious and in part pointed out more in detail hereinafter.
Accordingly, it has been found that the foregoing objects and advantages are attained in a detector mounting assembly having first and second support plates. A multidirectional pivot ball assembly pivotally interconnects the first support plate to the base of the spectrophotometer so that the first support plate is selectively pivotal about first and second pivot axes. A first set screw adjustment assembly is positioned for selective pivotal positioning of the first support plate about the first pivot axis. A second set screw adjustment assembly is positioned for selective pivotal positioning of the first support plate about the second pivot axis. A plurality of pivot ball assemblies pivotally interconnect the first support plate and the second support plate so that the second support plate is selectively pivotal about a third pivot axis. A third set screw adjustment assembly is positioned for selective pivotal positioning of the second support plate about the third pivot axis. The detector is mounted to the second support plate within the optical beam and the first, second and third pivot axes are relatively positioned and disposed so that the first set screw assembly moves the detector along a first arc generally transverse to the radiation beam for horizontal detector adjustment, the third set screw adjustment assembly moves the detector along a third arc generally transverse to the radiation beam and orthogonal to the first arc for vertical detector adjustment, and the second set screw adjustment moves the detector along a second arc generally along the radiation beam for focus.